Abstract In the course of our previous work, the interactions of two peptide fragments
(GluR1201–230 and GluR1231–259) of human glutamate receptor (GluR1201–300) polypeptide
with kynurenic acid (KYNA) were investigated by surface plasmon resonance (SPR) spectroscopy.
Besides quantitation of the interactions, the enthalpies of binding of KYNA on certain
peptide fragment-modified gold surfaces were also reported. In the present work, a
third peptide fragment (GluR1270–300) of the glutamate receptor was synthesized and
its interaction with KYNA was investigated by an SPR technique. This 31-membered peptide
was chemically bonded onto a gold-coated SPR chip via a cysteine residue. The peptide-functionalized
biosensor chip was analyzed by atomic force microscopy (AFM) and theoretical calculations
were performed on the structure and dimensions of the peptide on the gold surface.
In order to determine the isosteric heat of adsorption of the binding of KYNA on the
peptide-functionalized gold thin film, SPR experiments were carried out between +10
°C and +40 °C. The results on the GluR1270–300–KYNA system were compared with the
previously published binding parameters of the interactions of GluR1201–230 and GluR1231–259
with KYNA. The binding abilities of KYNA with all three peptide fragments immobilized
on the gold surface were estimated by a molecular docking procedure and the binding
free energies of these AMPA receptor subunits with KYNA were determined.